Thank you. Assuming that HMRC Stamp Office are correct, then you are liable to pay the stamp duty. HMRC do not usually calculate stamp duty, that is done by the solicitor. What we don’t know is what the solicitor submitted to HMRC.
Hence, it is most unlikely that any blame would attach to the revenue you do have cause for complaint against the firm of solicitors if they are still in business.
Can I clarify anything for you? Please rate the service positive so that I get paid. We can still exchange emails. Best wishes. FES.