Complex sentence: This was rejected in favor of requiring purchasers to make a telephone call to learn the price of the medallions on the day of purchase, after which the purchaser was to go to a post office the same day to make payment.
Split into simpler sentences: This was rejected in favor of requiring potential purchasers to make a telephone call to learn the cost for the medallions on the day of purchase. After the call was made, the purchaser was required to go to a post office the same day to make payment.