A bit of a disappointment...

Perhaps they just melted together. I have successfully taken the screws out of the base and then pried the tires off with a screwdriver. The tires seemed fine and I used some barrier like paper before reattachijg

 The 2 types of plastic interact many times.

@karl That's what it looks like happened.😟

I had this problem with a Neo model several years ago. The tires “melted” and had significant flat spots. 

I think you acted too hastily.   

I've had at least four 1/43 models arrive to me EXACTLY LIKE THIS.     It's simply glue from a hot glue gun that will NOT damage anything.    Some collectors feel more confident when their scale wheels are glued down.

I'd bet you $5 that model can be removed WITHOUT damage. 

@ed-davis This doesn't look like "melted tires"  to me, but it does look like "hot glue gun glue"  which can be easily removed without damaged as I noted above.   It may be all moot now, though, as the model might already be on its way back.     🤨 🤨

No this isn't glue, it's just what Karl said. The two polymeric components, tire and base, are not compatible. But use the back side of the knife and gently wiggle the tire up, preferably with the screws loosened but not removed, to avoid any dropped model problems. A very little bit of WD40 or shoe goo might help but be careful of the paint. Once you get it loose, you'll see the base did the melting, the tire should be ok.

@mg-harv What is shoe goo?

Lovely model so I hope it turns out ok for you. 
Steve

A well-known problem. It can be due to a reaction between the two types of plastic, which causes the tyres to soften and stick, or the mounting screws can be over-tightened at the factory and that can flatten the tyres simply by the pressure. For that reason many resin models from Neo and others are mounted to the base on spring-loaded screws and the advice is to ease off the screws until the springs lift the tyres a fraction clear of the base, to prevent  any interaction. Before moving or transporting a model (or before shipping it if you sell it) the base screws should be tightened to prevent the model breaking free. And presumably the new owner should be told to loosen them off again.

The same problem can occur if the model is removed from its base and put on a shelf made of some kind of plastic or acrylic. Hard to be sure what the plastic tyres will react to and stick to, although I have a few resin models that I put on display on wooden shelves (before I realised it is recommended to keep these models in their case) and they haven't stuck or flat-spotted. Yet.

And speaking of flat-spotting, heavy white metal models can flatten their tyres over the years, simply due to their weight. I keep a lot of Brooklins and similar models in drawers lined with foam which is thick enough for the base plate of the models to rest on it, keeping some of the weight off the tyres.

Certain 1:24th 'Mint' models that I own, indeed, have flat tires. FM's initial Mercedes-Benz 300 SL Gullwing, in silver, is a prime example. And if placed in a plastic case, like AMT's, the tires will meld together.

But looking at these photos, check out the second one carefully. When the tires melt into the case base, the melted portion is tire color - black. These two in the second pic, are up on the sidewalls and the tires have not sunken into the base. I believe Chris is correct - it appears as hot glue.

Posted by: @perrone1

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"I believe Chris is correct - it appears as hot glue."

It really does..... I see no evidence of melting tires or a melting base.   As I noted, I've purchased a few 1/43 cars just like this.....  hot glue was used to secure all four wheels.    🙄 🙄 🙄 

It's a bad pic (I know ) but notice the tires......  "glue!"    🙄 🤨 

This really does look like typical "tire melt" as we modelers call it. 

Which is a technically incorrect term as the plastic base has melted - not the tires. 

The tires remain a flexible material. The base is a more solid material. If you unscrew the model from the base - maybe leaving a thread or two of the screw attached - using a small blade regular screwdriver (just the tip) pry the tires from the base one at a time. Be careful and go slow as the tires will snap loose from the plastic base. Good luck!

John

Thank you for the feedback, gentlemen, and it is glue.  I did loosen the screws and attempted to gently slip a scalpel between the glue and the base, doing so with each tire, but nothing would give, and rather than have one of the wheels break off, I packed her up and the refund is already agreed.  No explanation was given, and I find it odd that anyone would do this when there are three screws in the bottom holding the model to the base.  A wee bit of overkill and more work for the buyer.

@graeme-ogg & @perrone  Thank you for those tips about the heavier metal cars.  I will employ a bit of foam under the chassis of the heavier models, to keep their tires from flattening.  I have noticed a couple of models online that have bases and I assumed this might be why. 

@ed-davis Oops - I meant Goo Gone, an all-purpose glue, paint, etc. remover.