This is to a person that wount leave me alone, i must do this before i get into problem, I have tried to be nice but does not work

Please translate this:

I know you are slow in the head, but please stop being a dog after me.
Please mature, grow up and leave me alone, hope this was your last sms! retard

 If he is turkish...im sorry for you. I was also in a same situation, tried all posibilities but didnt work...almost 2 years he was sending me sms(i never knew or met that boy). He will not stop bealive me ..even if you speak good or bad. Think on changing your number..

 I cant help you with this translation...in saying that even if you sen it will not stop him sending sms....I wait to tell me later if the message worked or not. Good luck

This is my try as I am new to Turkish........

Ben biliyorum siz ba

Biliyorum, kafan biraz aðýr çalýþýyor, ama lütfen peþimde bir köpek gibi dolaþmayý býrak

Lütfen olgunlaþ, büyü ve beni rahat býrak, umarým bu son mesajýndýr. Geri zekalý (I think you used it like saying retarded, otherwise it means to delay in Turkish)