Messages

Hi!
Everytime someone sends me a message, in the notification bar I get 'message memory full, incoming message rejected.' I really don't understand why because I have deleted all my messages and keep doing so incase I do end up having too many. I also read on a different website to delete all internet browsing history, cache, locations, passwords, etc. which I did and it worked for the first few times and now nothing I seem to do helps. I also get a pop up saying 'database storage low. Delete messages, contacts and calendar' but I don't have any events in the calendar, no messages as I'm not getting them and don't see how contacts take up that much space. I've even deleted loads of my unused apps and am now down to just the ones I use and have also erased my whole sd card so I can move apps to there and it has made absolutely no difference!
I hope someone can help, it's sooooooooo annoying! Thank you X

 

thank you, thank you, thank you!x