well 3pm this afternoon 13kg gas bottle ran out.hose just turned to wire.coldest day this winter so far.im a bit annoyed cos i thought it would last longer!!

so ive had 6 days using hot water averaging 6 hours a day using the heater so £4 a day.
ive heard some of you guys getting 2 weeks(10 days)out of a 13kg bottle or was it the 19kg one?
anyway theres a calor gas supplier just around the corner where most of my work is so got a refill for £24-50.
so potentially it could cost me near on £100 a month on gas to use it every day through my working month.
i have the temperature control on L5 slightly above minimum.not scalding hot but warm to the touch.i was expecting a few more days work before running out.
so realistically how long does your gas last??

many thanks in advance lads
dazmond