Incorrect prices being charged

Was at your Tygervalley store yesterday. Amongst others I bought the 200g Lindor assorted chocolates which was on the shelf for R6x.xx. After checking my slip at home (50km's further), you charged me R84.95. As a principle this is unacceptable. Prices needs to be fixed in the system before you put signage up in the store. Pls rectify this situation as soon as possible. It is ********* to charge customers more then what you advertise products for and blame it on a system problem like everyone else does. Come now WOOLWORTHS SA - I expect better from you.