if its a shopping mall then it is probably full of chewing gum so you will need a hotwash to remove this, it will probably need doing on a sunday to so take this into consideration as for price this can vary on drainage and amount of gum etc and can range from £1 a metre upto £4 a metre, if you are local i.e the north west and want a qoute to sub contract then give me a ring on my web site.