VAT payments allocated against surcharge before VAT liability

Had appeal hearing against VAT surcharge last week. The following day a bailiff came to client's premises demanding payment. Apparently HMRC allocates all payments against surcharges before allocating against VAT. Is this allowed?

I rang HMRC today and all they could tell me was the amount outstanding; they could not tell me which payments had been allocated against which liabilities. I asked to speak to someone more senior and he said he would get someone to call me back.

Is there anything else I can do?