Unfortunately, seamless roaming is not supported in the WAP4400N or the WAP4410N. In addition, other access points in the COBO line such as the WAP2000, WAP200 and WAP200E will only support fast roaming.
The WRVS4400N has a 3 year manufacturers warranty so it appears that you are within the warranty period. To begin the process, if you are not a registered VAR, please contact our support team at 800-326-7114 so they can authorize a return.
Unfortunately, the virtual SSIDs are not designed to broadcast so the WAP54GP is not the right solution to use. Only the main SSID can be changed to broadcast or not broadcast however support for the feature you require is available in the WAP200.