MTN and Nokia Charges me R300 for rejecting their quotation.

Hi, My Nokia 7 plus phone which I bought through MTN was taken to Nokia 4 months ago for fixing a charging problem and I was quoted R2580 for a phone that now costs R3000 so I had to reject the quotation and now they are telling me I must pay R300 for them to release the phone since I don't want them to fix my phone which is still under Nokia warranty. this is just ********ity and making me regret ever loving Nokia Phone. have been buying Nokia phone since 2005 and today this is the service I get for being loyal.