hi there
i am presuming that the shopping centre, currently has cleaners,
therfore they will have a specification.
i always ask the client for a copy of the current specifcation, and then you can build your specification, and improve on the current specification.
the reason why i did that was as follows.
say the current clenaer visit a premises 5 days per week,
and they state in their specification that they clean an item ie desks and chairs every day, there may well be an business argument that the desks only need to be cleaned every other day.
never be afraid to ask your potential client for a copy of their current cleaning specification.
if the client does not hasve a copy, then that is a unique selling point that you can exploit.
regards
martin