I want to get DSL NU. On MTNL Page, tariff given is SL - 590 p.m. OKMonthly rent if MTNL's CpE 80p.m. - OKDeposit for MTNL's cpe onetime and non-refundable - 500rs -- OK but what is safe custody charges ? is it one time/every month ? refundable or not ?dsl install and test charges -- 300 rs. one time - OK but refandable ?