Shouldn’t be a limit on any account when it comes to paying for something.
Easy to see what might happen. Only one of those 3 payments can be linked to the sale of the frame I think – via an invoice direct from ebay. Imagine the other two are done by goods payment.
You send the frame off. Tracking to some countries is very dodgy, I’m not sure about Russia but it isn’t one I would normally trust.
So he gets the frame, and he makes a claim that it’s damaged/not received. You defend it with the info you have, but you can only really do that on the payment linked to the sale, say £500. If you win you get to keep £500 but I bet the other two are claimed on and you won’t win as you have already won a claim based on the data you supplied. I could see you wining the first one maybe, but not the other two. So you are £840 down as a minimum.
Seller can claim damage as well, how is that going to be sorted out? You’re not going to have it sent back for £240 so you’ll lose out massively in some way.
Cancel the sale, even if you have to take the hit on the final value fee (which you shouldn’t as you specified UK only sale – did you do this the right way on the listing or just write it in the description? Either is fine but it’s odd how a Russian buyer saw it if you listed it properly as UK only) it’s money well spent.