This is de rigeur in payments; the brand guidelines for the big three credit card companies have similar things IIRC. They don't want you to say "Visa accepted here THOSE BASTARDS we prefer Amex" or otherwise interfere with their customer relationships while servicing your customer relationships.
There has been litigation around this routinely, including (IIRC) a US holding that says that merchants are allowed to say X is cheaper for them than Y if that statement is accurate.
There has been litigation around this routinely, including (IIRC) a US holding that says that merchants are allowed to say X is cheaper for them than Y if that statement is accurate.
Edit: that may have been reversed on appeal. https://www.bloomberg.com/news/articles/2016-09-26/american-...