Landlord deposit & utility bill issues

Hi,
Looking for some advice and hopefully a legal point of contact? In UK we have free legal services who can help you with such matters but not sure if that is the same in Holland?

I was renting an apartment this year and agreed with the landlord to terminate the contract early.

The agreement was as follows:
1. At final inspection on the departure date the Landlord would refund 75% of deposit as gesture of good faith to ensure the early termination happened on the agreed date provided they were happy with the apartment and there was no damage other than what has already been discussed by email.
2. Remainder of deposit would be refunded within 2 weeks as per the contract agreement.
3. Meter readings for gas/electricity/water would be taken on final day of departure and after contacting the companies and working out if a refund is owed to us, the money would also be returned within a few weeks.

The early termination agreement we both signed specifically started that the remainder of the security deposit would be returned within 2 weeks.

So now, after 5 weeks, the landlord is refusing to return the remainder of the deposit stating that they
are keeping it and using it to fix some damage that had happened while we were tenants; despite not being able to confirm whether it was out fault or not.

We suspect water damage occurred from pipes behind kitchen units and neither party could 100% confirm whether it was from water spillage or leakage.

They already returned the 75% and are threatening to sue if we try to claim the 25% legally.
Strange that they would refund 75%, when a security deposit by nature, is to be kept for any damage they believe to be the tenants fault!!

During the tenancy we were out of the country for 2 full months and therefore used no Gas, Electricity or Water. It was also summer time and Gas would have been minimal so we strongly believe there will be a refund due from all utility companies. We have good reason to believe that the landlord will try to steal this instead of return it to us legally.

Does anyone have any experience in such matters or able to put me in touch with some Dutch authorities that can assist?

Many Thanks
Bob