Monzo declined chargeback and section 75 for CC purchase

Hi all, looking for something advice.

In June I moved to a new property and hired the services of a company to make a bulky waste collection at my old property. The flat was mostly empty, most of the furniture there was to go. The purchase was made online, on their website, with a credit card, and each piece of furniture was individually priced, so they knew what to collect. The total amount was about £180 in a single purchase, but individually no item was above £100 - the most expensive was their service fee, about £70. I also added a note to the order asking to be contacted 30 minutes before collection so I could be there for it.

Comes the day of the collection, I received some SMS saying their team would arrive around 12 PM, so I make sure to be there at that time. I get there, and all my furniture was gone (1 piece of furniture should not have been taken). I had a cleaner and landlord in there (last day of the tenancy) and they told me the collection team arrived around 10 AM, said they had spoken with me over the phone and that I confirmed everything was to go, so they took everything and left.

I have tried resolving this with the company I hired, but every time I speak with them they pretend to be working on it. I managed to convince one of the customer support agents to send me an email acknowledging they’re are aware of the issue and are investigating it, but since then every time I ask for an update they just say they’re working on it and can’t provide more updates. When I ask them about getting that information through email, they say they have management orders to not do that - one even told me the agent who sent me that original email got in trouble because of that. On that first email acknowledging the issue, they confirmed the item taken by mistake was unrecoverable.

Monzo has been unhelpful, and I spoke with Citizens Advice as well. They recommended writing them a letter, but I feel I’d be ignored all over again. I have reported the company to Trading Standards.

Would this be considered theft by negligence? I haven’t gone to the police because the missing item is not that expensive and holds no sentimental value. The furniture missing cost me £129, so along with the service I paid for (and did not exactly get), I’m down ~£300.

What are my options here? I have photos of what was in the flat, so not sure if small claims is even an option (or worth it).