Can not resolve their own accounting issues

The most pathetic service ever - had blood tests done. Paid for the test in cash (R902.00). Then Lancet decided to double-charge me for the same tests at an additional cost of R 1702.00. For the past 2 months, I have been phoning, mailing, sending SMS to get this matter resolved - only to be kept on line for 40 - 187 min at a time - and then to get the excuse - my manager is too busy - they can not answer the phone. I will escalate the matter. This is either desperation or incompetence - either way, it does not reflect well on the company. And seeing that management is too busy to resolve the matter, I will advertise this company's lack of service to potential clients