(Reuters) -UK’s Royal Mail on Monday offered a new conditional pay hike to its grade employees belonging to the Communication Workers Union (CWU) before the union rejected the proposal, citing “unacceptable changes”. The offer includes a 7% salary increase over two years, plus a lump sum payment of 2% of pay this year, but was subject to CWU agreeing to several changes including working on Sundays, start times and flexible working. “It (the offer) includes more unacceptable changes and a derisory 7% two-year pay offer that is well below projected inflation for both years,” CWU said in a statem…