MTN phone number given away

Had a contract for more than 20 years, went to prepaid and could not use it for a few months ( work related )( i was still using the numbers whatsapp with duel link ) called to find out the number has been given away( i did not know they give it away after 3 motnhs ) , with no way of getting it back, that number is linked to important apps/bank/business etc. Would never recommend again in my life, call center is one of the worst i encountered in my life. No help at all.