Social Security Survivor Benefits?

My twins turned 18 on June 22nd this year and school did not get out til the 24th. Knowing that they do not graduate til next year they both did the paper work to extend benefits til they graduate, they did all the proper forms and mailed them in. They received a letter saying that their benefits would start in June, in their name, and then every month on the 3rd Wednesday.

In July, last week actually, they both got a letter saying their benefits are stopping this month. Is it because they are 18 and it is summer and they are not in school full time again til September? Will they have to do all that paper work over again?