I was recently working with the Google Shopping Content API and kept getting the “Quota Limit Exceeded” error message. After much googling, it didn’t seem like there was a definite answer to the problem. I didn’t know if the error message meant that I was sending too many requests per time unit or if there was a finite number of product information rows that could be uploaded to Google servers.
After much troubleshooting and calling Google, it looks like they have a finite cap on the number of product information rows that you can upload. To increase your quota, you must shoot them a phone call and relay the error message to them. In my case, I had to call twice because the number of products that I was working with was too large for one call due to company policy.
tl;dr Call Google.