Here's a professionally redrafted version of your hotel feedback that clearly conveys your dissatisfaction while maintaining a polite tone:
Hotel Feedback:
I’m disappointed with the experience at this hotel. Despite booking online, the room provided was clearly among the least desirable—small in size with a very cramped bathroom. It felt bookings are intentionally given the lowest category rooms, which is unfair to customers who book in advance and in good faith.
Additionally, the hotel manager was not cooperative when we raised our concerns. Instead of addressing the issue or offering a resolution, the response lacked courtesy and willingness to help.
This experience fell short of expectations and does not reflect the hospitality standards one would hope for. I would not recommend this property unless clear improvements are made in both service attitude and room allocation fairness.