The FIDO roaming information is totally misleading and designed to sneakily steal from their customers.
When you go to the FIDO roaming webpage in the section pay-per-use they say 9.99$/20MB in the Zone 2 countries (Europe). What they did not say is that the rate is only valid for 24h and reset again and again. Thus, I used 5.52 MB in three different days and I was charged with 29.97$. So, in their information they are hiding the most important piece of infromation abour their roaming rates, which is a very "convenient" way to charge outrageous rates or force you to use their daily roaming rates plans.
Welcome to the community!
Sorry to hear you were not aware of how the roaming fees work. However, I don't think they were intending on misleading customers. That information was provided in the Full Details section of their Travel page:
It has always been good practice to look into any Full Details or fine print for any service or product you choose to use. You can also view their Terms & Conditions here.
Hope this helps 😀