Change email address withno accsess too the email linked?

I have always used FireFoxNow the email that I use to login to mozilla accounts. I cannot gain access the email I use too login.Lost my mobile phone and along with that my sim/number too gain access too my mail account!! See no matter what I do, It asks me to verify my gmail/outlook/yahoo etc I would lobe to gain axx too my main email address but at the moment I cant get A replacement sim with the number I need too gain/verify because. Too get A Replacement ssim with the number I always used for years now.. they "the mobile provider" want the pin code that came with the sim pack that came years ago!?! Like I have looked every were for that sim card pack to get the original pin code too get a replacement. Shur it was years ago and that pack with the original pin code that of course I changed it too A code I would like. So now i am stuck between a rock and a hard place. No original sim, They wont accept that it was years old "Original pin on the sim pack" and I have changed the pin from the original pin, lost the original pin! So I just lets say for mozilla want too change my email too my new email because I cant login to my gmail, even do I know the password etc but google wants me too verify threw the phone I lost or the number I lost. Can anyone advise me on how I can at the very least change the mail i use to login here too an new mail I had to make. Kindest Regards, Steve.