I use the cruise line websites. If it is a Royal Caribbean Cruises International cruise line then the prices are the same regardless of who you bought it from.
If it is Carnival or another line then your TA may have discounted the fare but the base price will always be the same.
If the price on the cruise line's website is lower than what you paid then call your agent.
You ALWAYS must do an apples to apples comparison. If you booked a Cat D1 balcony you can only look at what D1's are going for. You can look at higher category cabins and if they have dropped to what you paid then it may be worth it to call your agent and see if you can get the higher category cabin.
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"There is a great difference between being well traveled and just having been to many places." ~Me