When an EU regulation or directive is replaced, the successor law will generally clarify that references to the old law should be interpreted as references to the successor law. That is also the case here.
The old law is Regulation (EU) No 531/2012
The successor law is Regulation (EU) 2022/612
The successor law contains the following article:
Article 23: Repeal
Regulation (EU) No 531/2012 is repealed.
References to the repealed Regulation shall be construed as references to this Regulation and shall be read in accordance with the correlation table in Annex II.
That annex provides a mapping between articles in both laws.
So, if your contract references Regulation 531/2012, you can interpret that as a reference to Regulation 2022/612. If your contract mentions specific articles of the old regulation, you can use Annex II to find the corresponding articles in the new regulation.
This does not mean that the new regulation is necessarily applicable in your case. You mention that the dispute “is” from a time when the new law applied. However, the question is not when the dispute was raised, but when the alleged breaches occurred. If the matter were to be laid before a court, the court would apply the old law for breaches while the old law was in force, and the new law for those breaches while the new law was in force. This could lead to the same or distinct results. I haven't read the laws in question, so it could also be that these regulations apply to the formation of contracts and not conduct during those contracts, so that the old law might remain in effect until one contractual period is over (e.g. if you have a yearly contract that will renew on 2022-12-01, the old regulation might be applicable until then).