After less than 3 months with severe deficiency

I bought myself an extra something this expensive battery for my 2 year old Xperia mini pro, so it just does not give the problems one often has with spare batteries. According to the description of this battery also has an overheating protection. But after less than 3 months in use (yes, the battery life is slightly longer than the original battery) Battery overheated this repeatedly and then unloads itself. Since I made the counter test with the old battery, which does not have any problem, this article is the problem real shame.