Veg and pellets are supplementary to a guinea pigs diet and should be kept limited. Veggies should be around one cup/50 grams per day per pig. Pellets are one tablespoon per pig per day. Don’t leave them with constant access to pellets or veg.
They need to eat more hay than anything else with it provided in unlimited amounts day and night - over 80% of their daily food intake needs to be hay.
The link below explains
Long Term Balanced General And Special Needs Guinea Pig Diets