Few days ago a PPC campaign manager complained to me that the banners she got from her client were in an "unusual file format". Asked me to check it out because she couldn't open the file and she really needed the banners.

I kid you not, it had a .rar extension...
She, at the age of 30, had no idea what WinRar was...

Yep. Most non-tech don't know what rar is, so they get a pass. Rar is only well known among techies. When dealing with the non-tech world, give them zip. They don't want to have to go and find and install a special app to uncompress a file. It's a little known thing in the tech world called customer service. We serve them, not the other way around.

I once submitted a rar file to a magazine company who were going to send a mailshot out for my company. I got an email back saying they couldn't open it and it needs to be a HTML file and I need to send the images also...

All faith was lost in the company that promised so much that day.

I can't figure out why website traffic and sales have plummeted. How can I find out the reason and fix it? Advice on how to be?

Now separate point tools don't work like they used to. You need to do everything in a complex, and seo, and contextual advertising, and also order a site audit, so that you can see all the real work of specialists and the growth of clients. You can order a complex of these services in the agency https://seotwix.com/ppc-services here affordable prices for all services, so if you have only a young start-up website, you can not worry about the budget.