Freedom of movement in EU for NON-EU with Stamp 4?

Hi everyone,
I am hoping to get some help here!

I am a NON EU national married to an EU citizen. I have been issued a Stamp 4 EUfam residence card by my local GNIB for the past few years. Renewal was NEVER a problem, within 2 weeks it was all done.
This time things are different: When my card came back, the stamp was only "4" without the "EUfam". After requesting an explaination I was told, that I never had the right to an EUfam stamp, it was issued by mistake to me.

My question now: Do my travel rights within the EU (together with my wife) remain the same? i.e. not needing a visa to travel to Italy.
Would our marriage cert be suffient evidence that I am travelling as a spouse of a EU citizen?

I believe I do need a re-entry visa now to return after our holidays?! We are travelling in less than a week and it looks to me there is no realistic chance to have this sorted before?1

Grateful for any advise!