QATAR atrocious customer service

My experience with Qatar has been awful. I have been shunted from pillar to post. I booked a flight, with pre seating and then changed my mind and flew without pre-seating. Qatar issued me vouchers, to use within 1 year for the pre seating cost of R6300.00 Due to unforeseen circumstance, I was not able to use the voucher for another booking, so before the expiry date I contacted Qatar, on the email they had sent me and had no response. I then contacted Qatar in Fourways Johannesburg and they contacted Qatar Head Office. I was told after numerous emails and visits to the office in Fourways, Qatar incorrectly informed me, that I had used the vouchers on the my booking, which I had not. Qatar recognized I had not used the vouchers and I then asked for the vouchers to be extended so I could use them at a later date. After months of back and forth, I was told that unfortunately I had forfeited the R6300.00 vouchers and Qatar would not refund me. I will not fly on Qatar again due to this atrocious service I received as a paying customer. I am out of pocket R6300.00. Not acceptable.!!