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Good morning. I certainly understand your feelings and desire to pay what others are paying. However, the landlord/management is not legally required to rent every unit for the same price. The goal is of the landlord is to rent each unit for as much as possible, so that they can maximize their total profits. Even though you signed the rental agreement around the same time and the apartments are the same, they are not forced or required to tell you what other tenants are paying or rent to you for the same price. I know it is not ideal or what you wanted to hear but it is the truth and they are not forced to rent it to you for the same.
Yes, if you signed up for the monthly service, it should be a one time fee. However, I encourage you to contact customer service to confirm, since I have no knowledge of that. As far as your follow up question, it is not discrimination by trying to charge you more, since they are in the business of making money. Moreover, they may argue and say you accepted their offer and did not make a counter offer, so you voluntarily agreed.
Yes, you could ask for a better rate and address the issue with discrimination. However, keep in mind, if they DENIED renting to you, it would be an argument but discrimination and racism is not necessarily charging you more then someone else but the argument could aways be made. Thank you again and please let me know if there is anything else. If not, please just remember top rate my help at the top, so the site will give me credit.