cash or bank guarantee for electricity usage as stated in clause 10.1 is required from the buyer for the initial supply of electricity at the rate as specified by the seller however, if it turns out later that the mentioned guarantee amount is than two times of the highest monthly payment of the fee for utilizing the electricity of any month in respective yearly cycle, the buyer shall arrange for the increase of cash or the bank guarantee to be not less than two times of the highest monthly payment of any month in respective yearly cycle within 15 days from date of notice given by the seller