Bluetooth connection for text messages on 2016 Toyota tundra

I have 2016 Tundra (Limited) and have a problem with Text messages connecting my Apple 5s phone to my Truck. It has been frustrating and so far little help from Toyota Customer Service. I have an Apple 5s phone, and I have to disconnect Bluetooht on my moble phone and then recommect each and every time to get text messages on my truck. This is very frustrating and most annoying. I spent over an hour with the Toyota Customer Service represenative trying different things but nothing has resolved my issue. I still have to disconnect Bluethone on my phone, and then recommect to get and read messages on my phone. This has to be done each time I shut off the truck!
The Toyota CSR suggested that the problem may be related to my phone. Have others had a similar problem and how did it get resolved?

There must be a resolution.....any help please!