Is it justified for ID to ask for additional charges after signing contract?

[tanjiro 0]

I would like to check whether it is a normal practice for IDs to ask for additional payment after signing contract? 

My experience was after signing contract, ID forgot to add in an item that cost $2K into the final price and I compromised with payment of half the difference.

Then despite a few reminders that power was cut to the unit and asked whether I am required to take any action, ID did not respond and realised reno couldn't start due to no power supply resulting in a 2 weeks delay.

Now ID is telling me because I do not have a loading bay below my block I have to pay for additional haulage and debris clearing cost.

Basically I am not satisfied with the competence of the ID but in this case where home owners usually have paid 60% of the contract value before work even started, what are our options?

What constitute reasonable additional payment to the ID? While we may exercise our rights and make complain to CASE, this would probably result in delays and an unhappy relationship.

 

 

[AppleCrumble 45]

No it is not common, a professional ID would already know what are the costs involved, because once a contract is signed its done, he cannot go back and change the quotes, any ID that does that after contract signing is not worth his salt in my opinion