Is always very important for us to keep all receive and also even parking receipts we get during each appointment ,I keep mostly everything in a box named rsd stuff, funny ,have so many papers and lately I'm putting everything in order by dates, also,copy of dr reports so I built my own profile,became handy for any offices errors,happens once and I learned a bad lesson since then no more undocumented receipt on my file box, hope you don't get such of scams again and by the way,always call dr office to confirm they are actually contacting the right person, blessings to all and gentle hugs,with love Jesika .
Check your credit record, in California for example ,we get some mails saying some dr office stuff used the ss number to get credit ,make sure you are not a fraud victim.
Also verify with Medicare if back then any gap was met and you never receive the notification,all possible scenarios can happen ,make sure you don't let things that way ,good luck.