Return and Exchange/Refund Nightmare

I placed an order for clothes on Yellow sub Trading on the end of October. My clothes were delivered and collected on the beginning of November. Some items did not fit how I like so I began the return and Exchange process... Followed their rules to a T. The couriers collected my order on the 7th of November as arranged and since then it has been multiple emails back and forth... Calls back a forth with Yellow sub Trading trying to get assistance. No luck. Now they have even gone as far as ignoring Whatsapp's, emails,calls etc... you'll hold on their help line untill you're next and the they'll ignore your calls until the timer hits 15-17 minutes then they will cut you off. Very frustrating,they are ignoring clients and *********** people. Poor customer service and it shows they don't care about their customers