My cass diagram is it correct?

Hi all
i want to know your opinions about my project class diagram is it correct ? should i change some thing ?

in fact i did my internship in a telecommunication company wich have many distributors ,each distributor distribute to his shops cards phone ,then the shops by these cards phone
each cards hone bought is asociated to an offer , in fact, each offer has a cotegorie( voice or data) and a type(prepaid or postpaid)
an offer in add is associated to one or more withdrawal the following class diagram is it correct please ?
thanks a lot for any answer