Reimbursement/ compensation for holiday accomodation

LilNic

We have recently returned from a holiday in Spain..We booked our accomodation through Booking.com in February. Photos and description described a 3 bedroom apartment with a private terrace. 
On arrival some 6 months after booking, we found that the apartment was in the middle of a construction site with new houses being built directly outside our property. This had a significant impact on our holiday as the building works started at 7am with machinery waking us up. We were also unable to use our private terrace throughout the day. 

Our issue is we were not made aware of the works ahead of our arrival, it was not minor/unplanned work and had clearly been ongoing for some time. Had we been made aware of the work, we would have cancelled and had the opportunity to book a more suitable and relaxing holiday. We were denied that opportunity..

After arriving in the apartment, we found a qr code from the owner apologising for the work and suggesting we sit by the pool as it was much quieter there! The work could still be heard by the pool and was far from the relaxing holiday we had planned and looked forward to. We also incurred extra costs over the holiday as we were unable to sit around the pool and therefore spent more money out of the complex. 

We took many photos and videos at various points in the day to support our claim that we have been mis-sold this holiday. 

Our booking was with booking.com, but the apartment was operated under Zap Holidays. We complained on the first day to Zap but failed to receive a reply. After 3 days we chased and eventually received a reply confirming the owner had agreed to a 15% reduction! Having looked at their website we later found that the 15% offered wasn't reimbursement but a discount given to all new customers (as they have detailed the works on their advertisement for the property). 

On returning home we spoke to Booking.com who said they would contact Zap Holidays. A couple of days later we received an automated email from Booking.com saying they were unable to get hold of them and suggested we contact them directly. I sent a further email suggesting that the 15% discount should be honoured and requested a refund of £100 per day for the inconvenience, upset caused and the loss of enjoyment of holiday (including the additional costs incurred). 5 days later we have still not heard back from Zap. I chased Booking.com again yesterday who claim that the refund needs to come from Zap Holidays and that they have issued a further request for them to look into this. 

I feel like we are going around in circles and nobody is accepting responsibility. Where do we stand? 
Is it worth contacting our credit card company to investigate?