can’t access amazon seller account because i changed my phonenumber

Hi all, first of all, i am a big amateur with accounts on amazon/facebook etc, i always mess it up

i changed my phonenumber as an amazon seller, now i can’t access it, amazon helpdesk says, ow it’s easy just login and change phonenumber, sure, but first i need to get in with the old number which i don’t have

​

then they advice, make new account with new phonenumber, and add your old user email, but doesnt work, so now the new number is also attached to a account that cant make a new user because the storename is occupied

​

so is there any way to get this fix, that would really be a great thing