Last week, Grameenphone and Robi were involved in an intense battle to buy five megahertz of spectrum in 2100 band during an auction.     The top two operators were particularly keen on getting the spectrum as they were the last block of the unused spectrum in the band. The country also sold all of its wavelengths in the 1800 band. So, the two operators went to great lengths to post record bids as they needed the spectrum as they look to improve service quality amid surging subscribers.