Also be sure your mail adress with which you order Digital River (maybe same , maybe not than avast mail ident)
Check for SPAM in your (DR order) adress , already 2 times you have not received a Digital River mail (after ordering and after phone call) when you should have received them.
Did you tried to contact them by other way than phone call?
https://gc.digitalriver.com/gc/ent/login.do (if you forgot/haven’t ident/pass , ask for)
or
https://store.avast.com/DRHM/store?Action=DisplayContactFormPage&SiteID=avast