Hi Claire,
That has never happened to us, but i would suggest taking the faulty test strips back to the chemist and get them replaced, the chemist can then get intouch with the maker.
Glad you had a spare meter, its a real panic when youv'e no test strips, happened to us last week, entirely Andrews fault! He had threw empty test strip container back into his storage box, you can imagine my panic and language when i found it empty last Monday morning!! Eventually found an old meter with test strips still in use, he won't be doing that again.
Take care,
Suzi x