Cell Phone Tradein

Sent My cell Phone for trading for the new Z5 flip. Service consultant at Cell C agateway advised me of the R15000 trade in price. Regener8group giving me R10000. And told money will be deposited on 9th October 2023. When I saw the add and emailed them the R15000 tradein. Spoken to a lady by the name Kasendra who told me she can cancel the trade in for R10000 and redo a new online form for the R15000. Automatically on the 27th of September they deposited R10000 into my account. Not acceptable. I want the balance R5000 for my tradein