Formal complain

Hello Peter. I've experienced where the the dentist told me that the "chair that am sitting on it's very expensive chair I won't even find it in any dental surgeon in my area.the problem stated when I ask a detailed statement for my insurance where he didn't have a problem to do cause is something that I ask when I go there ,so he asked me how much did I pay for cleaning teeth then I said R400 then he said thats not possible that they can charge that amount and I explained to him that my first time I came to his dental surgeon the price was R350 for cleaning teeth I went on telling him before I came here I call your receptionist and asked her how much is to clean the teeth ?then the lady said R400.then that's when he said the chair that am sitting on it's a very expensive chair and he was very rude I went back to his receptionist and ask her how much is to clean the teeth the lady said the very same thing which is R400 and I said your boss say isn't R400 so whose telling the truth here the lady tried to explain to me that maybe he forgot to tell me(receptionist)to increase the prices so that j can inform the patient.okay fine I was angry and disappointed by the treatment he gave me.so last month on the 12/10/2020 my partner went there to take out his teeth they help him but he forgot to take the receipt, the receipt that will help us to ask for refund at our insurance because he used his own money to pay for his appointment.now we can't get our refund because thy can't assist us on giving us the receipt now thy even blocked my calls cause they know what I want from them.last week during the week I called to ask them to give me the receipt the receptionist said I will send the receipt via WhatsApp even today i didn't receive the receipt and the detailed statement with the stamp.i will appreciate if I can get the detailed statement with stamp on it and the receipt.thanks