Bangle GPS Power management

From various bits of code I was found on the web I think the sequence has to be something like.

    UBX_CFG_RESET();  // do a factory reset to ensure my setup is taken
    wait(20);
    UBX_CFG_INTERVAL(29,5);  // PMS
    wait(20);
    UBX_CFG_PM2();  // with same intervals but in ms instead of seconds
    wait(20);
    UBX_CFG_RATE(17);  // set the rate but may not be required
    wait(20);
    UBX_CFG_SAVE();  //  save the configuration as it gets reset on wake up
    wait(5);