Account nightmare

The Accounts department is unavailable. I paid for a procedure, and a week later get a statement for much less than what was paid. There is no information on the statement and no indication of payment made. I have called (as there is no email address as stated in the statement) and cannot/will not be assisted by anyone except the person dealing with the account, this person is always busy, so on hold AGAIN going on 20 minutes. Hire more staff if this is the issue, we pay a premium for ********** service.