Builder Dispute

In 2017 we had building works carried out that didn't go entirely according to plan or schedule.
Substandard work was carried out and areas totally missed from the contract which the owner of the company acknowledged and in agreement but the refunds offered were worth peanuts in comparison to what was a reasonable figure for the actual works would be.

Since the member was founded through FMB, we initiated the complaints process via FMB.
After a few months of back and forth with the founder of the building company via FMB, FMB simply closed the case (FMB simply acted as a forwarding service throughout the process and did not have any guidance or any mediation).

I posted online about my poor experiences with FMB and an employee of the FMB came across my post and got the case that was closed it re-opened (we think he was told off for this as we never heard back from him again).

FMB now decided to listen to our problems (it went up to the complaints director) in detail and felt there were grounds for negligence and sent us to CEDR to mediate for a resolution.

Based on personal circumstances and over another 2 months of not getting very far with the mediation process, I agreed in the the mediation process to accept a settlement figure from the founder of the building company.
The figure was far less than what I could probably have got in small claims but due to personal stress at the time along with this process was getting to my family, so I opted against the Small Claims option.

The contracted and legally binding agreement from the CEDR process stated that the owner of the building company had to pay two separate figures, first in 30days and second after 60 days and also provide certs that were omitted during when the works were being carried out (not sure why the builder scheduled it like this but he was not happy paying it all up front)

30 days passed and he made the first payment but when the 60 days passed he did not pay on time and certs were not provided.

We chased for the 2nd payment with no response so we went back to CEDR whom advised it had to go back to FMB. We contacted FMB and they said they would be arranging a meeting with the founder of the building company with 10 working days...

The meeting took place two days ago (4weeks post 2nd payment due date) and on that same evening the founder contacted me to advise he was having difficulties paying and required another 30days.
I contacted FMB after reading this email to ask them what was the process for breach of contract and how we could escalate this matter?

Ironically the founder contacted me this morning and to my surprise advised he had made the final payment and will be in touch soon to arrange the certs.

I am not happy that the legally binding contract was broken and it was only after suggesting to the FMB that I wanted to escalate things, that payment was made within 12hours of me sending that email.

Do I have ground to take the founder to the small claims court for all the inconveniences he has caused and breach of contract, even though he has finally made the final payment today but still has outstanding certs to provide?

My personal circumstances no longer exist so I do feel he deserves the book thrown at him but not sure what would be the right action for this.

Regardless of both payments I have received, he has still got away with short changing me...