If your heel pads have become worn down over time then replace them with the Fizik Heel Skid Plate Two Hole (Pair). The set includes both the left and right heel pad. Not compatible with R3B. Available in two sizes: 36-42 (EU) and 43-48 (EU).
S$26.00
or 3 installments of S$8.67 with 
S$24.00
or 3 installments of S$8.00 with