How do agencies handle currency rate changes?
Reputable agencies quote and contract the trip in a stable foreign currency (often USD) to keep the deal insulated from local economic fluctuations. After your deposit is made and the agreement is signed, the total price stays locked and guaranteed regardless of local inflation.
If the Sri Lankan Rupee depreciates heavily before you arrive, you will not get any refund, and similarly you would not be charged more if the Rupee strengthens. This fixed USD amount gives you budget certainty for your vacation planning.