Sudden increase in program fees and unwanted services

We just completed a program with GlobalCrossroad
The project with the local Association, but dealing with GlobalCrossroad was not pleasant at all.
Surely they were reactive to provide us with information before we subscribed. We subscribed for 2 weeks advertised at 213$ per person (+299$ registration fees)

After paying the initial 99$ registration fees, we received an invoice mentioning:
- 293$ program fees, 28% more than advertised
- 25$ per person for transfer fees from the airport where locally it costs no more than 3$ by taxi
- Spanish classes we never asks for
- mandatory travel insurance for which we never had any details
- 5% surcharge on the credit card

We asked to review the invoice to remove un requested Spanish lessons and the travel insurance as we already had ours
Luckily we noticed the Spanish lessons. We heard from other volunteers they did not notice the trick and got charged.
And It took us 3 months to remove the travel insurance from the invoice

It is our fault not having noticed the increase in program fees on our invoice. Indeed as they are to be paid in cash to the local coordinator, they did not appear in balance due figures

We actually realised when the local coordinator asked us for the money. We sent email to GlobalCrossroad to correct the discrepancy. GlobalCrossroad suddenly lost their reactivity and we had to wait till the very last day to get an answer, and a negative one on top of that.

Iam warning here potential volunteers who might apply or already applied on programs with GlobalCrossroad that they might face tricks in their invoice and be asked to pay a bit more than they thought