Samsung J5 and grand prime malfunctioning

Samsung J5 and galaxy prime are not working correctly and jeep saying storage space full. The repairs centre manager Deon is not of any help at the Durban Nandi Drive repairs centre. Had to take the J5 back after two days of receiving it back and now the grand prime is not functioning again one day after collection. Deon basically told us it cannot be repaired because its an entry level phone and basics like whatsups and facebook cannot run on it. There are no other applications on. Need urgent assistance please as this is not accetable as sales personal sold the device under the pretense that whatsup and facebook whould function with no problem. The voice of the customer also told me those two apps should easily work. Deon is telling us its not repairable. Please assit with the next step? Thank you Judy Scheepers