Seller refusing to pay

I recently purchased a leasehold property in England. During the buying process, I learned of planned major works in the building. I inquired with my solicitor if these works had begun and was informed they had not. Based on this, it was agreed to reduce the purchase price.

However, after moving in, I received a bill for these major works. Upon investigation, I discovered these works were completed nearly a year before my purchase was completed.
I attempted to recover the full cost of the major works through my solicitor, but the seller claims the leaseholder informed them the works had not commenced (without providing any proof). The seller's solicitor is now ignoring my solicitor's emails. So , I filed a small claim but couldn't be served as the seller has moved out from that address. I only have their solicitor's contact information.

Is there anything I can do to recover the money or should I take it as lost?

Thanks