Review on 📟 GNC GB-8561 Bluetooth(R) Heart Rate Monitor: Track Your Heart Rate Wirelessly by Stephanie More

I can't connect this to my phone. I have tried a new iPhone 7 and also an Android phone. iPhone won't connect at all and Android randomly stops working. I asked the community for advice on which app to try (Sakar is the app I know for this product). The seller replied and advised to check the manufacturer's website. I tried to find this information but to no avail. As far as I can tell the heart rate monitor is made by a company and brand GNC with no support website for GNC. Since I paid for it and can't use it, I'd be grateful if someone could suggest alternative apps that would work with it.