Based on my experience, Globe Telecom replaced my white iPhone 4S in 2 weeks. Although I was told that it could take up to a month to have it replaced. They gave me the same color. I suggest that you ask them if you have an option to do so.
You were told that it takes 1-2 months but you have to consider the availability of the stocks and the delivery of the device specially if it comes from overseas. We never know.
The unit replacement is usaully the same color as your original unit unless you have made a prior request which may or may not be fulfilled depending on the availability.
I've had an iphone replaced back in 2009 and it took Globe around 2 weeks (not over a month). The 1 or 2 months may be the maximum it would take them if the supplies have run out specially with the iphone which is always in demand.
How can I request via email in Globe?
It is ridiculous to ask customers to wait for their replacement phones for 1-2 months. Globe should have prepared their inventory for situations like this. This is the obligation of the operator. The problem is -- they will lure you into purchasing these phones without being honest about their after-sales.