I've had few A.B.S parts and they were all extremely crap.
AKR performance ( Dutch shop) have good selection of parts.
It's easy to find out if it's caliper or cable gets stuck. When it gets seized again just release hand brake, take the wheel off and and have a look. If it's bad caliper you will see that handbrake it's still applied and you will be able just detach the cable as it's going to be loose. The try if you are able to pull manually that handbrake spring on the caliper. If you are able to release it that means it's caliper