Dear ........... ,
With my apologies for inconveniencing you a lot before , since I would like to come to Gratts as a self-funded person , I will be grateful if you could kindly send me a new invitaion letter (for the period starting from August 28 , 2018).
Please also let me know if it will be possible for that center to provide a dormitory for us for a limited time.
Thanks and best regards
قسمت زیر هم رفرنسی است از وبستر جهت مزید اطلاع خودتون :
to cause problems for someone
I don't want to inconvenience you any further.