If you're thinking of buying one of these InsulCheck clip-on timers for your insulin pens beware. They are expensive and the two I bought only lasted just over 7 months. Refund refused...
You should contact them again and remind them what it says on their website in the FAQ section:
What happens if my InsulCheck Classic stops working?
We offer a 2-year unconditional warranty on all products. If for any reason your device should stop working within 2 years after purchase, simply Contact Us and we will arrange a replacement InsulCheck timer to be sent to you. https://www.insulcheck.com/product-support