With all due respect to the majority of advocates who are undoubtedly sincere and ethical in their practice, I must point out that especially in metro cities, many advocates do not specify their fees to the client and merely ask for a lump sum up front 'on account'. Later on they ask for more lump sum amounts. Many of these advocates do not even give any invoice or receipt unless the client keeps insisting. Some unscrupulous advocates charge 'per date', regardless of whether the bench is sitting, they or the OP takes adjournment, or for whatever reason.
At the very least the advocate as a professional, should specify his charges in detail before the client signs the vakalatnama. This will also avoid ill will at a later stage.