You should not have cancelled if you still want the card.
My last year's experience is that system reject, hotline appeal reject, I called to cancel card. 2 weeks later retention unit called to say waive.
Got long lecture from me because I already lost quarterly rebate because did not spend in mth 3. Told them suppose to be goodwill but experience end up upsetting customer because makes them feel like have to beg the bank to waive.
Also told them that UOB card is quarterly rebate and linked to UOB account bank account for interest. Any delay cause the customer to lose card rebate. You think you just lose the customer for the card but actually may also lose the customer's bank account