Your second paragraph was probably the problem - by raising an issue which is related to re-registrations and then linking it to "amended" entries (i.e. corrected), for which there is only the original entry to order. They have answered as though you are talking about re-registrations.
- Corrected/amended entries, and re-registrations are two completely different things that are unrelated and shouldn't be discussed together, although it is a very poorly understood subject, even amongst professional researchers. Any corrected/amended entry may be shown as an occasional copy in the indexes but there is only one entry, and one reference, which if ordered as a certificate should show whatever the correction has been.
- A re-registered entry has two (or sometimes more) completely separate entries, often years apart, that will have different references and can have different information on them and can sometime take some finding in the indexes. Those are the ones that GRO still persist in sending a certificate from the later entry even when the older one is ordered despite it being raised as a problem with them on a number of occasions, and them promising not to.