paraphrase

Comment

It’s a letter , so it needs to be in the correct format with the name and address of client and your company’s address at the top

Ypur letter concentrates on the factor that influence the extra design cost, but essentially your client will want to know weather ( a) it can be done , and (b) how much it is going to cost him overall so what are your specific proposals ?

A brief indication of potential cost may persuade the client he doesn’t need a theathre that badly !