Delayed Response from Claims Department

I took my car for routine annual maintenance service and claimed from IUA through the car dealership. The car dealership informed me last week Friday that they had submitted the required invoice & claims and had spoken to an agent at IUA, Nunu. I called multiple times to confirm the invoice had been received by IUA and was told by agents at IUA that they had not yet received the invoice. In the meantime, I’ve been unable to collect my car from the dealership because payment has not yet been received. This therefore delayed my entire trip I had planned, costing me lost accommodation. After calling multiple times and following up with the IUA on several occasions, I discovered that IUA had infact received the invoice last week but “couldn’t locate it”. I have received no apologies from the agent (Nunu) or her manager Charles. On top of this claims agent was rude on the phone. I sent an email to her manager and also received no response. The service received from the claims center at IUA has been appalling