I agree that's a complete dick move on their part. But when you see "We may, from time to time at our sole discretion and without notice or liability, create, amend, change, or delete any content from the IGP Offerings." at the top of their terms, that should raise a *huge* red flag before you reach for your wallet in the first place.
I don't know about your jurisdiction, but mine has "unfair contract terms" legislation. One of the Act's cited examples of a term which is unfair and therefore not enforceable in any contract is a term which:
has the object or effect of
[...]
enabling the seller or supplier to alter unilaterally without a valid
reason any characteristics of the product or service to be
provided
Quoting from government advice on interpretation of this law:
Where circumstances could prevent the supply of the
goods or services agreed (or a version of them that the consumer has
indicated is acceptable) then the consumer should be able to cancel the
contract, and receive a refund of prepayments.
A term which could allow the supplier to vary what is supplied at will –
rather than because of bona fide external circumstances – is unlikely to be
fair even if customers have a right of cancellation and refund. The
consumer should never have to choose between accepting a product that is
not what was agreed, or suffering the inconvenience of unexpectedly not
getting, for example, goods for which he or she may have an immediate
need, or a long-planned holiday, just because it suits the supplier not to
supply what was promised.
If you have similar legislation in your jurisdiction, you may want to challenge the decision not to supply what you paid for in court. You may be entitled not just to a refund, but also compensation.
IANAL; this is not legal advice; consult a legal professional before commencing court proceedings; etc.