Which cable?

[#1]

Im upgrading cables as ive had the same modem cable for years.
It connects from the bt faceplate (fibre) to the bt modem.
not sure what one it is but its quite thick and has larger sheilds on the connectors.

can i use a cat 6 or cat 6e cable to replace it?

[#2]

Quote

can i use a cat 6 or cat 6e cable to replace it?

You can but cat 5 with RJ11 connections would probably be adequate.
Just out of interest would the cable be very long that you intend to use for that or would a fairly short one do the trick?
Adam

[#3]

current set up is two 5m joined with a connector.
dont want to run wireless from downstairs because my ps3 is upstairs and i want that wired.

[#4]

?
The optimum setup from what you describe is an as short as possible ADSL/VDSL cable from the faceplate to the modem, (IIRC the modem comes with a 1.5m one), then as long an ethernet cable as you wish from the modem to the router.