Grand Prime Plus - should be a minus!!!

I recently bought a galaxy Grand Prime Plus and only found out afterwards that the phone has an Internal storage of 8MB and the Operating system takes up 7.5MB, I have a SD card in my phone and have set it up so that everything saves automatically to the SD card, but I still constantly get messages that my memory is full. I sent an email to Samsung to help me and this was their response - how can they sell a phone that has no space :

The phone has only 8BGs on bored and that can not upgrade. Even if you should get a memory card it won’t help cause most of the apps are on the phone. In the long run the phone will give you problems of Internal storage. It would have been best if you got a SAMSUNG A20 the phone has 32GBs on bored and you wont have any memory problems. The SAMSUNG A20 in our shop is going for R3299.99 if you do come in the Sandton SAMSUNG shop & ask for LLOYD HLANGWANE I will be able to help with everything. And would be able to advise what to look for when buying a new phone and which will be good vale for money.