to have/having

Neither, unfortunately.

You don't need both 'to have' and 'to be'.

I went to my cousin's pharmacy to have my prescription filled.

I went to my cousin's pharmacy for my prescription to be filled.

(The second sentence, while ok grammatically, sounds very unnatural!)

or another acceptable alternative is:

I went to my cousin's pharmacy to get my pr

to have is the one you want. It's an infinitive of purpose. It answers the question "Why?" or "For what purpose?"

CJ

Thank You very much Califjim !

Why " having " is not correct ?

Once again, thanks

for ... ing is not used to show purpose. The for often implies exchange, like this.

You give me money. In exchange I give you a book.
You pay for the book.

You buy me lunch. 'In exchange', I thank you (give you thanks) for lunch. I thank you for buying me lunch.

The idea of exchange can blend into t