Hi there
I think you have to judge whether they are comfortable first off. If they are then the choice is keep them knowing that a boot in this price/quality category will last 2 to 3 years before leaking or starting to show signs of falling apart or try for money back.
I've had three pairs of boots in this price class by three different manufacturers... Le Chameau, Technica & Magnum all made in China. The Le Chameau were the worst only lasting 6 months... the Technica lasted better and served for 2 seasons of Alpine hikes.. The Magnum's are best so far due to a Vibram sole and have been the most comfortable and so far pretty hard wearing. After 2 years of less intensive use than the Technica's they are still going strong.
The next choice is for a better quality boot.. BUT it will cost you twice your Karrimor's price. Brands to look at Lowa, Meindl, Altberg..etc I think from now on I will always opt for leather for a serious boot.
After my above experiences I've since bought some Lowa Combat boots. They are brilliant, comfy and hard wearing, they are just a quality item. I picked them up for 130 quid from
www.polmil.co.uk but they generally go for around £170, which when you compare the difference in price with say the Karrimor's.. you get way more for your money.
I spent probably around 300 Euros on my previous pairs of boots, but I'm sure the Lowa's will outlast them... so price is only relative.
cheers
Gareth