I would not know how long, it is better to go and ask (if it is within your reach) because by phone it is almost impossible for them to give you information, they rarely answer the phone.
Less toempo the extension, also I do not think they are doing renovations at the moment. I had the opportunity to go to Washington and the attention was super cordial, warm and they helped me a lot.
An extension takes less time because you already have your passport
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