Disappeared between their contract - Complain against The Design Bay Studio

Hi all. I would like some advice/contacts if you can help. I am based in UK but hired The Design Bay Studio to help with social media for my business. Let me say, ; the path was all downhill from here. They didn’t create any strategy, any plans for my brand, neither did they expect me to! In 6 months, they didn’t come up with a single plan whatsoever. I paid them for 6 months, and agreed to 4 creatives per week, i.e. 16 per month. As my partnership with them began on 21st august, in the month of Oct- November, they only posted 9 creatives, in Nov- Dec only 2 and then they disappeared completely around January. they ignored all my WhatsApp messages and call, and they didn’t reply to my email at all. As you know, for a start-up especially a brand in fashion/ wedding industry, social media is necessary. however, they didn’t answer to me at all, until I called their India office from UK. I finally got through them in March. First time I called with my name, they said- Anushi (the lady responsible for dealing with my brand) isn’t around. The second time, I called changing my name, and Anushi answered- and said, they have partnered with a very big client, and that is the reason they weren’t able to respond, I replied back to her saying, I am their client too, but she gave me a vague response and said she will discuss with her CEO and get back to me.
After suffering huge loss for not being able to have a steady social media due to these fraudsters, that know how to earn money scamming vulnerable people, I asked for a refund for the 3 months of creatives left pending. to which they replied in March, after their 2 months disappearing act, that they are happy to continue with the posts but can’t provide me with a refund.
I fail to understand, how is anyone able to continue with an agency that suddenly disappeared for 2 months also ignoring all calls and messages, only to get back and say we can continue again with posting! However, that isn’t the point of the business, as it needs active social media, not just putting posts whenever one feels like! How do I recover the idle time caused by them on my brand’s page?
After replying to their email with my concerns , I was disregarded again only to get a reply from the founder Mallika Kejriwal in April- “With regards to the refund of the creative's not met, that wouldn't be possible unfortunately we have already completed 6 months of the project - the time-frame is over, but the creatives haven't been done & to ensure that falls into place - we're happy to design the creative's that are pending definitely!
I fail to understand how it was my fault that they didn’t complete their job within the time-frame and disappeared within the time-frame and now due to the contract signed, they are not willing to refund whatsoever . I am still waiting for them to reply to me since April despite calling them a lot of times.
Honestly, I had given up expecting anything from them, but I realised, it’s not fair that fraudulent companies like this can get away whenever they like.
What would you guys have done in such a case (I have all the proof through my email conversation, yet they are not willing to understand )