Can any help me with this. I am a web designer That builds sites for clients using wix. The only thing I cannot figure out how to do is to allow my clients to pay for their premium site hosting without them giving me all of their private info and credit card details. Ideally I would build their site, send them a link to pay and boom all done. However sending a link only says the person needs to sign in. There must be an option available to allow someone else to pay without needing to be signed into wix?? Help please 
Hello Kelly,
This is not a Wix Code Issue and we try our best to keep this forum just for that, try contacting support here .
You have two options:
Remote - Download Team Viewer or a similar software. Transfer the site ownership to them. hop on Team Viewer and set up the premium plan allowing them to input their credit card information. Once done transfer the ownership back to you or keep it with them.
Local - Have a meeting with them and using their laptop (after you transfer ownership) make the site premium. Transfer ownership back if needed.
Best,
Majd