[Contact Form 7] redirect to Several Differents url

I use contact form 7.
I use : on_sent_ok: “location.replace(‘https://www.paypal.com/cgi-bin/blablabaaaa’);” but my clients are always redirected to the same paypal payment.

As I have several products with different price, I need to redirect them to an URL which will be different in function of the product they choose in a Drop-down menu. [select* service include_blank “TOUR1” “TOUR2” “TOURS3” “TOURS4” ]

I have already created severals url with Paypal. Now I need to redirect the payment in function of the choice of the drop-down menu.

I imagine I must write a function and call this function in on_sent_ok.

I have no acknowledgment in PHP. Who knows how to do this redirection ?
Would be great.
Thanks.