Smarty also has a spending cap (could not find a link to the article, so copied and paste it) :
About your Spend Limit
Why we’re applying Spend Limits to your account
Casey avatar
Written by Casey
Updated over a week ago
The Payment Services Regulation 2017 restricts how much you can spend on premium rate services. This aims to make payments safer while protecting you and your money.
Spend Limits on SMARTY currently cover spending on premium rate calls to 084 and 087 numbers.
The limits are:
A limit of £40 per single transaction.
A cumulative limit of £240 for transactions made over the course of a month.
Note: you can only make calls to premium-rate numbers if you have purchased an Out of Plan add on.
For example:
If you purchased £50 worth of Out of Plan add-ons to make calls to an 084/087 number, the call would cut off once you’ve spent £40 on a single call. You’ll be notified once you’ve hit 100% of the £40 signal transaction limit.
You’ll then be able to start a new call and be limited to £40 again. The total you can spend per month is £240 and you’ll need to wait until the next calendar month for this limit to reset.
We’ll notify you when you’ve reached 100% of the £40 single transaction limit and 80% then 100% of the £240 transaction limit.
FAQs
Can I increase this limit?
This Spend Limit is a legal regulation and can’t be removed or changed and resets per calendar month.
Why have you put this limit in place?
It is an Ofcom requirement that we must adhere to.
When will my limit reset?
Your limit is reset every calendar month.