I think my freezer has broken!

My mother bought back some bits and pieces (including some fish) for the dogs from the supermarket the other day, but they don't seem to be freezing at all
I have a big order coming on Friday and I don't want it all to go off.
I've looked on ebay and preloved for a second hand freezer but can't find any close and can't afford a new one.

If I filled the freezer with ice is it likely the food will keep fresh?

Yikes! I did have an episode where someone turned the power to the summerhouse off without telling me it was off for maybe a day or two before I discovered it when our human food went a bit soggy. The dogs' stuff actually stayed pretty well frozen though as there was a large quantity - the volume of it all packed together helped keep it all cool and stopped it from defrosting much at all.
Have you tried Gumtree as well as Preloved? Friday ads, Freeads, even the ads in your local supermarket/newsagent? Maybe even a "wanted" ad on each of them - someone may have a freezer going spare that they haven't got around to advertising yet.

I've just gone and had another look at it and theres a little dial I have turned up hoping to make it colder..
Theres some ice around the top so I have turned it off and propped open the lid to defrost it for a few days in hopes that it will work again.

I've found one on preloved that I've asked if it's still available just in case.

You need to buy a proper thermometer thingy for that freezer, it's the only way to know whether it's working properly or not. Frozen food should be stored at -18deg or under, nothing higher Sainsbury's do them for fridges and freezers.