I have just purchased a BT8500 Advanced Caller Home Phone from Amazon (Less than an week). Two of the four handsets no longer retain their charge. Once the handset is placed in its cradle (charging pod), the handset itself lights up and switches off repeatedly. The base station also emits a red flashing light. i have left the handset on charge for just over 48 hours. My initial thought is that the batteries need replacing??? Has anyone else experienced this?