Unable to login due to phone number

back in 2018, i sold on amazon and i want to use that same store to sell again if possible. The problem is the account is associated with a phone number I no longer have access to. This means I am unable to login to sellercentral or Amazon in general. I have contacted their service and they said to contact seller central – But how can i do that if i cant even log in?

I am just going round in circles here, any advice?