Sage Accounting cannot get their email system sorted out

For months now, you have had a delay (not delay - no delivery) on emails from Sage Accounting to certain email addresses (i.e. ALL email addresses). And you just cannot seem to get it sorted out. My clients are not getting invoices, which means that they cannot make payments, which means there is a delay in orders, which means that we as a company looks bad due to your system having issues sending emails. I have tried different email platforms - outlook, gmail etc as alternative delivery addresses, with zero success. Also, there is no delay - the invoice emails simply does not get delivered. I have sent you NUMEROUS emails about this, via the system, directly, via Facebook, and you just do not get this sorted out. I have been using your system since 2012, and as you can imagine, by NOW, after having this issue for so long, that you cannot sort out, I am extremely frustrated and disappointed. I cannot believe a large company like Sage failed to get this issue sorted out timeously. I have already paid for the year in advance in September 2020, so can you kindly let me know how to get my money back - I cannot work with you any longer - your system is failing my company.