The assigned Bluetooth COM port has nothing to do with the GPS you are using. It is a function of the Bluetooth stack and it assigns the next free COM port of the ones it has available.
I just had to do something similar in XP. If you are using the built-in Windows Bluetooth stack, you may be able to change the COM port in Device Manager. Right click on 'My Computer' and choose 'Properties'. Choose the Hardware tab and 'Device Manager' button. Scroll down and click on the '+" next to Ports(COM & LPT). You will see a list of the assigned COM ports.
Right click on the COM port you want to change (13 in your case). It will say something like 'Standard serial over Bluetooth link (COM 13). From the drop down choose Properties. From the resulting box, click on the 'Port Settings' tab and 'Advanced' button. There will be a drop down in the bottom left that lists all the COM ports if you use the little arrow next to it. Change the COM port to one below 9 making sure to choose one that doesn't say 'in use' in brackets. Ok out back to Device Manager (you may get warning messages about changing it but just click OK).
Try your program with the new COM port and see if it works.
Send
Navmii a nasty email about using outmoded COM routines!!
IF you are using a Bluetooth stack other than Windows (eg Toshiba), let me know as the procedure will be different.
Terry