Freelance Contract Payment Dispute

yes the payment has always been late

We have been working as freelancers for Fragile. In the last month, we discussed issues about continuing full-time next year, potentially reducing to 2 days per week. We had finished our existing projects without starting new ones, so work concluded for the year when I handed everything in on Friday. The office is closing this Friday for the year, which has been planned for about a month. During my time there, my personal laptop was stolen along with other items, preventing me from working. Work offered to buy a temporary replacement laptop that they would sell once I bought my own. They are now using this situation as another reason for halving December's retainer. I need advice on whether to stand my ground and pursue the full amount. I'm not looking to take legal action—I just need to understand my rights. For context, my company is small and my bosses are friends, which makes their approach more shocking. I'm mentioning this because I don't believe they will take legal action.

*.*. The Agreement shall commence when signed by both Parties and shall terminate upon completion of the outlined phase by December 31st *, unless terminated earlier as provided in Clause *.* or *.* hereof. *.*. Either Party may terminate the Agreement at any time, effective immediately. The Contractor shall pay the Collaborator for any Work performed up to the effective date of termination if such Work was performed in accordance with the Agreement. *.*. Either Party may terminate the Agreement by written notice of termination to the other Party, effective immediately, if the other Party fails to remedy any material breach of the Agreement within * working days of receiving written notice of such breach. *.*. Since it is in the mutual interest to continue the cooperation after the agreement has been fulfilled, both parties undertake to hold ongoing discussions to define whether and how the cooperation can be continued.